Pearlescent

Ingredients with this function are needed primarily for visual effect: they give the product a soft glow, optical depth and silky shine. In decorative cosmetics, such components make the tone, shadows, highlighters, lip glosses and varnishes more "lively" and light-scattering, and in care formulas they can improve the appearance of the product, making it more attractive and visually more "premium". On skin and hair, they do not so much take care of themselves as they change the perception of the coating: they help to create the effect of smoothness, freshness, even glow and sometimes gently mask irregularities due to the reflection of light. The European CosIng database identifies pearlescent as a separate cosmetic function, that is, it is about giving a pearly appearance to an ingredient or finished product. (single-market-economy.ec.europa.eu)

Most often, this effect is provided by mineral or pigment systems, for example Mica and combinations based on Titanium Dioxide. Mica reflects light well and gives a transparent shimmer, while titanium dioxide enhances brightness and opacity, so together they are often used in pearlescent pigments for makeup and hair products. The FDA specifically mentions mica-based pearlescent pigments as an existing category of pigments used for decorative visual effects, and also recalls that cosmetic ingredients and dyes must be used within the framework of safety requirements and current regulations. Therefore, this function is primarily related to the texture and appearance of the product, and not to the treatment of skin or hair. (fda.gov)